New DIY Mid High (90deg) - AKA PM90

Dominique Duttilleux said:
Has anybody actually tested the HF950 with the RCF ND950, or used it in a project?
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Test Bench: RCF ND950 Neodymium Compression Driver and HF950 Horn

In this Test Bench, Vance Dickason characterizes for the first time a transducer from RCF. In this case, a combination of the ND950 1.4 neodymium compression driver along with the HF950 injection-molded composite horn specifically designed to work with the ND950. This article was originally...
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Dickason's measurements are better than most of the large format drivers he has tested.
There's usable output above 10kHz and breakup doesn't look nearly as bad as some 3" diaphragm drivers.
On speakerplans people have reported favorably on the sound quality and somebody posted a raw response curve that looks excellent.
I know a guy that uses several ND950's to great satisfaction in a low/medium SPL application, from 400Hz and up.

It's available from various online retailers for about €260.
 
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I have used the ND950 1.4 from 800 Hz and up. Horn used was the 18sound XR1464 not the best horn for such low crossover, but it worked.
They sound pretty nice definitely for the money, I'm planning on using them again with a different project (dual 10").
 
Hi Dominique,

I could not see the paid article, but I did read the PM90 tread.

Having read that I feel I should point out a couple of things-
  • The PM90/60 is designed to be pole mounted – as such there are some compromises.
  • They are only designed to go down to 100Hz
  • Because of the bent mid horn, the mids should not operate above about 750Hz
  • The mids are not designed to be flat without DSP correction.
  • The 12” drivers operate in their piston range.
  • Because the 12” drivers are operating in their piston range you can correct their response with a DSP and they will still sound good.
  • The choice of the BMS4594 other than sound quality was its ability to operate at the very low crossover frequency needed. This is what limits the number of other suitable compression drivers and horns.
 
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Hi Peter,

The guy who wrote the article (Christian Boche) chose the RCF because it's cheaper.
He somewhere stated he could buy these for €170 each, which would be close to dealer purchase price.
Obviously, your design is well thought out for the intended purposes: high SPL, pole mounted, relatively lightweight.
As you may know, the ND950/HF950 is used with a crossover at 650Hz in RCF's TT-5A (45-20000Hz).
 
Hi Dominique,

Fineally got to read the paid article - thats fantasic, great to see other people having success with this design :)

...and yes I was aware that RCF used the ND950/HP950 in the TT-5A ... and the HF950 in the TT-2A with the ND850. That's how I knew before I ordered the HP950 that they would work as low as I needed :).

Its also great to know that the ND950 works well in the PM90 design. I think some where at the beginning of this thread (or the PM60) I suggested it as a cheaper alternative.
 
B&C DCX464 will probably be 2-3 times more expensive than the ND950.
The driver is expected to become available at the end of June.

Graphs:

BC_DCX464_(Frequency_response).png


BC_DCX464_(Impedance).png
 
Ti Liptak said:
@Bennett Prescott - is there an ETA on US availability?

Carl, if it performs better than the BMS, equal pricing is great!
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Very good point! I do however feel a little miffed on behalf of BMS who I believe patented this design - please correct me if I am wrong - only to have B&C do a 'Chinese rip-off', so to speak. I find it very odd that the prices here in the UK are within 0.2% of each other and the specs are so very similar. B&C seem to have no advantage whatsoever on paper, and should have made a point of publishing distortion data (if better than BMS) since they seem to be otherwise so closely matched. Perhaps the DCX is licensed from BMS, but surely that would have to have been declared...
I for one would not wish to spend out identical money on a brand-new product when a very good and established one already exists. I don't have the financial means to buy a pair 'for fun' so I'll have to wait a year or so until the DCX has been out in the field a while. Cheers, Carl.
 
Carl Klinkenborg said:
Very good point! I do however feel a little miffed on behalf of BMS who I believe patented this design - please correct me if I am wrong - only to have B&C do a 'Chinese rip-off', so to speak. I find it very odd that the prices here in the UK are within 0.2% of each other and the specs are so very similar. B&C seem to have no advantage whatsoever on paper, and should have made a point of publishing distortion data (if better than BMS) since they seem to be otherwise so closely matched. Perhaps the DCX is licensed from BMS, but surely that would have to have been declared...
I for one would not wish to spend out identical money on a brand-new product when a very good and established one already exists. I don't have the financial means to buy a pair 'for fun' so I'll have to wait a year or so until the DCX has been out in the field a while. Cheers, Carl.
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The B&C design will almost certainly have better distortion characteristics. The impedance traces also clearly show a different design to the BMS. The B&C design also seems to promise a much nicer crossover region where both diaphragms work together, as opposed to the rather steep and sudden transition in the BMS driver. As usual, though, the BMS seems to be a touch louder, and seems to have more LMF extension. I also suspect the B&C will be easier to design a successful crossover for, given that you accept DSP correction (I whipped something up in about 5 minutes).

My point here is that this appears to be a different design with different compromises and technologies for the same product segment. While there is clearly some IP overlap, BMS and B&C design their compression drivers in different ways with different "secret sauce". I think there's enough of a difference to say they are clearly different.

I would separately object to calling the DCX a "Chinese rip-off" in any way. Besides that it is not manufactured in China, it's not significantly cheaper or of less quality. While the first coaxial compression driver for this segment was clearly the BMS, I think that B&C have spent major R&D time coming up with what they think is their best version of a 1.4" coaxial compression driver.

Finally, I'll admit I'm a bit of a B&C fanboy, and would like to say now that I imagine the B&C will sound better in part because of the bias from my experience with the BMS 4594HE and several B&C compression drivers. While I was planning on selling my 4594HE, I am seriously considering waiting to sell it until I can get a B&C DCX464 to compare.

P.S. Am I the only one having trouble reading "DCX464" and thinking "DCX2496"?
 
The BMS was the perfect driver for the PM90/60 because it could produce high SPL and operate down to the low frequency (600-700 Hz) need to mate with the low frequency bent horn while still having pristine VHF up to about 20KHz.

I believe BMS Patented this technology in 1997 and patent has has now expired. It was a great idea that worked very well.

Over the last 20 years there has been a lot advances in computer modelling techniques and materials that should allow B&C to produce a much better driver based on this idea of having two co-entrant sources, HF +VHF exit through the same horn throat.

There were however a few issues with this design that I'm sure B&C were aware of and I suspect have improved. As a result I also expect this new B&C driver will be better - louder, lower distortion, better water fall plots etc. and make the PM90/60 even better ;)?

… so I have a some on order to try.
 
Thanks for your analysis Max - many things there I had not considered.

I'm sorry that my tongue-in-cheek and far from literal metaphor of a 'Chinese rip off' was not taken with the intent intended - I too like and use B&C, and they have been most helpful with information regarding the DCX464. It would be insane to think it is no better than the BMS, but the launch of the B&C driver just seemed so flat, with potential customers such as me wondering why I should take the risk.

BMS are one of the few driver manufacturers to offer distortion plots, and I feel that if B&C had done likewise, many concerns would have been allayed. I suspect that the design and production arms have done a fantastic job; the marketing, less so...

Looking forward to A/B comparisons.

PS. Yes, I get that Behringer connection too!
 
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